diff --git a/CONTRIBUTORS.md b/CONTRIBUTORS.md
index f571704fc..d0523a6b2 100644
--- a/CONTRIBUTORS.md
+++ b/CONTRIBUTORS.md
@@ -10,4 +10,5 @@
 | oakleybrunt     | Oakley Brunt      | Met Office  | 2025-12-19 |
 | harry-shepherd  | Harry Shepherd    | Met Office  | 2026-01-08 |
 | DrTVockerodtMO  | Terence Vockerodt | Met Office  | 2026-01-08 |
+| mo-lucy-gordon  | Lucy Gordon       | Met Office  | 2026-01-14 |
 | MetBenjaminWent | Benjamin Went     | Met Office  | 2026-01-15 |
diff --git a/applications/lfricinputs/fortitude.toml b/applications/lfricinputs/fortitude.toml
new file mode 100644
index 000000000..c4e5e9ab7
--- /dev/null
+++ b/applications/lfricinputs/fortitude.toml
@@ -0,0 +1,13 @@
+##############################################################################
+# (c) Crown copyright Met Office. All rights reserved.
+# The file LICENCE, distributed with this code, contains details of the terms
+# under which the code may be used.
+##############################################################################
+
+[check]
+
+file-extensions= ["f90", "F90", "X90", "x90", "pf"]          #check these file types
+
+select = ["S101"]
+
+output-format = "grouped"                #group results by file
diff --git a/rose-stem/app/check_fortitude_linter/file/fortitude.toml b/rose-stem/app/check_fortitude_linter/file/fortitude.toml
new file mode 100644
index 000000000..c4e5e9ab7
--- /dev/null
+++ b/rose-stem/app/check_fortitude_linter/file/fortitude.toml
@@ -0,0 +1,13 @@
+##############################################################################
+# (c) Crown copyright Met Office. All rights reserved.
+# The file LICENCE, distributed with this code, contains details of the terms
+# under which the code may be used.
+##############################################################################
+
+[check]
+
+file-extensions= ["f90", "F90", "X90", "x90", "pf"]          #check these file types
+
+select = ["S101"]
+
+output-format = "grouped"                #group results by file
diff --git a/rose-stem/app/check_fortitude_linter/rose-app.conf b/rose-stem/app/check_fortitude_linter/rose-app.conf
new file mode 100644
index 000000000..452d4c196
--- /dev/null
+++ b/rose-stem/app/check_fortitude_linter/rose-app.conf
@@ -0,0 +1,2 @@
+[command]
+default=$CYLC_WORKFLOW_RUN_DIR/bin/fortitude_launcher.py -s $SOURCE_ROOT/lfric_apps
diff --git a/rose-stem/bin/fortitude_launcher.py b/rose-stem/bin/fortitude_launcher.py
new file mode 100755
index 000000000..3acca0a2b
--- /dev/null
+++ b/rose-stem/bin/fortitude_launcher.py
@@ -0,0 +1,87 @@
+#!/usr/bin/env python3
+##############################################################################
+# (c) Crown copyright Met Office. All rights reserved.
+# The file LICENCE, distributed with this code, contains details of the terms
+# under which the code may be used.
+##############################################################################
+
+"""
+Launch fortitude on list of directories. Run on all and print outputs.
+Fail if any style changes required.
+"""
+
+import sys
+import os
+import subprocess
+import argparse
+
+
+def launch_fortitude(config_path, app_path):
+    """
+    Launch fortitude as a subprocess command and check the output
+    """
+
+    command = f"fortitude --config-file {config_path} check {app_path}"
+    result = subprocess.run(command.split(), capture_output=True, text=True)
+
+    print(result.stdout)
+    return result
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(
+        description="Run fortitude on all applications. If "
+        "application/fortitude.toml exists use that file, otherwise "
+        "use one in rose-stem/app/check_fortitude_linter/file. "
+        "Print output, raise error if any changes required."
+    )
+    parser.add_argument(
+        "-s",
+        "--source",
+        help="The top level of lfric_apps directory.",
+        required=True,
+    )
+    args = parser.parse_args()
+
+    failed_apps = {}
+
+    for top_dir in ["applications", "science"]:
+        applications = os.listdir(os.path.join(args.source, top_dir))
+        for app in applications:
+            print(f"Running on {app}\n")
+            app_path = os.path.join(args.source, top_dir, app)
+            config_path = os.path.join(app_path, "fortitude.toml")
+            if not os.path.exists(os.path.join(config_path)):
+                print("Using universal config (toml) file."
+                      " (Some apps use their own config file.)")
+                config_path = os.path.join(
+                    args.source,
+                    "rose-stem",
+                    "app",
+                    "check_fortitude_linter",
+                    "file",
+                    "fortitude.toml",
+                )
+            result = launch_fortitude(config_path, app_path)
+            if result.returncode:
+                # prints the app run on if there are errors of any kind
+                print(f"Checking: {app} \n", file=sys.stderr)
+                if not result.stderr:
+                    # prints if no other/config errors are found
+                    print("Found lint errors:", file=sys.stderr)
+                    # prints the lint errors
+                    print(result.stdout, file=sys.stderr)
+                if result.stderr:
+                    # prints if there are other/config errors
+                    print("Found non-lint errors: \n", file=sys.stderr)
+                    # prints the other/config errors
+                    print(result.stderr, "\n\n\n", file=sys.stderr)
+                failed_apps[app] = result.stderr
+
+    if failed_apps:
+        error_message = ""
+        print("\n\n\nSummary: Fortitude found errors in"
+              " the following repositories:\n", file=sys.stderr)
+        for failed in failed_apps:
+            error_message += f"{failed}\n"
+        sys.exit(error_message)
diff --git a/rose-stem/site/azngarch/groups.cylc b/rose-stem/site/azngarch/groups.cylc
index dfd4c44d9..6a861533a 100644
--- a/rose-stem/site/azngarch/groups.cylc
+++ b/rose-stem/site/azngarch/groups.cylc
@@ -9,6 +9,7 @@
     "scripts": [
         "config_dump_checker",
         "style_checker",
+        "fortitude_linter",
         "extract_checker",
         "site_validator",
         "validate_rose_meta",
diff --git a/rose-stem/site/meto/groups.cylc b/rose-stem/site/meto/groups.cylc
index fa3a62574..2e3efc1cf 100644
--- a/rose-stem/site/meto/groups.cylc
+++ b/rose-stem/site/meto/groups.cylc
@@ -9,6 +9,7 @@
     "scripts": [
         "config_dump_checker",
         "style_checker",
+        "fortitude_linter",
         "extract_checker",
         "site_validator",
         "validate_rose_meta",
diff --git a/rose-stem/site/nci/groups.cylc b/rose-stem/site/nci/groups.cylc
index f3f6e5457..da9f508df 100644
--- a/rose-stem/site/nci/groups.cylc
+++ b/rose-stem/site/nci/groups.cylc
@@ -22,6 +22,7 @@
     "scripts": [
         "config_dump_checker",
         "style_checker",
+        "fortitude_linter",
         "extract_checker",
         "site_validator",
         "validate_rose_meta",
diff --git a/rose-stem/site/uoe/groups.cylc b/rose-stem/site/uoe/groups.cylc
index f0c011f3b..40b68874b 100644
--- a/rose-stem/site/uoe/groups.cylc
+++ b/rose-stem/site/uoe/groups.cylc
@@ -10,6 +10,7 @@
     "scripts": [
         "config_dump_checker",
         "style_checker",
+        "fortitude_linter",
         "extract_checker",
         "site_validator",
     ],
diff --git a/rose-stem/templates/graph/populate_graph_scripts.cylc b/rose-stem/templates/graph/populate_graph_scripts.cylc
index 41c90a45c..1f70d9baf 100644
--- a/rose-stem/templates/graph/populate_graph_scripts.cylc
+++ b/rose-stem/templates/graph/populate_graph_scripts.cylc
@@ -51,6 +51,7 @@
     {# All other scripts have the same simple graph. These are: #}
     {# * config_dump_checker #}
     {# * style_checker #}
+    {# * fortitude_linter #}
     {# * site_validator #}
     {# * rose-stem_lint_checker #}
     {# * validate_rose_meta #}
diff --git a/rose-stem/templates/runtime/generate_runtime_scripts.cylc b/rose-stem/templates/runtime/generate_runtime_scripts.cylc
index bd602ad7c..a1ce6f61a 100644
--- a/rose-stem/templates/runtime/generate_runtime_scripts.cylc
+++ b/rose-stem/templates/runtime/generate_runtime_scripts.cylc
@@ -43,6 +43,11 @@
         inherit={{inherit.str|upper}}
         script="rose task-run --app-key=check_style"
 
+{% elif "fortitude_linter" in task %}
+
+        inherit={{inherit.str|upper}}
+        script="rose task-run --app-key=check_fortitude_linter"
+
 {% elif "extract_checker" in task %}
 
         inherit={{inherit.str|upper}}